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DIY corner traps: panel-like or tube-like construction?

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Posted on October 14, 2009 at 19:23:25
LewinskiH01
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Joined: December 7, 2008
 Hello.

The ongoing post on DIY acoustic panels has gotten me all fired up on the subject. It seems I would first need to make a couple bass traps for the corners behind the speakers.

16" tube traps are a bit massive on looks and would be a hard sell with the wife, as the audio system sits in our living room, so I'm thinking corner traps and would like to ask you a few DIY questions:

Are corner traps just regular Jon Risch-like panels placed on a corner, or do they have a structure behind?
Are their cross-sections fiberglass triangles, ressembling a tube trap but with a triangular section?
Do they need to be air tight?
What size of a corner trap would yield the same absortion as a 16" tube trap?

Thank you!

Reply to your specific questions, posted on October 16, 2009 at 17:43:29
Jon Risch
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 Q: Are corner traps just regular Jon Risch-like panels placed on a corner, or do they have a structure behind?

A: As noted in the 1st part, wall panels are not bass traps.

In my opinion, a bass trap is a device that is specifically designed to absorb and dampen lower bass frequencies very effectively. It can either depend on a sheer mass of absorbing material, or it can leverage some other absorbing principal, as do the ASC type bass traps.

The typical wall panel is just not thick enough, nor is it large enough to absorb or dampen very much lower bass frequencies.

You mention a Corner Trap, rather than a Bass Trap. This implies a bass trap, rather than a wall panel, but again, there has been so much confusion on the subject of bass traps vs. wall panels, that it is understandable.

Assuming that you meant a bass trap, then no, a bass trap is not the same as a wall panel, ala JMR or otherwise.

Q: Are their cross-sections fiberglass triangles, ressembling a tube trap but with a triangular section?

A: I mention a simple version of a bass trap, using 2" of 705 semi-rigid panels placed in an equilateral triangle shape, bondd together at the edges with a sealant/adheasive, and with top and bottom end caps to create a simple yet effective sealed pressure absorber structure.

It is not as effective as a true ASC type bass trap, but is closer than most simople wall panels would perform in the corner without being air-sealed into place.

Q: Do they need to be air tight?

A: Depends on what you are trying to do. If you want to create a pressure action bass trap, then yes, the "panel" would have to placed in the corner straddling the corner, run floor to ceiling, and be sealed all around the edges. This would essentially be a single-sided pressure action bass trap.

The beauty of the ASC style device, is that it has such a large surface area, all of which comes into play during it's action, and thus on a cubic or even a psuedo-square foot basis, is hard to beat for sheer bass damping and absorbing power.

That;s the other aspect of a cylinder-based pressure trap, when it 'runs out of absoprtion' at some low frequency, below that point, it STILL dampens and helps control the lower frequencies.

Once a wall panel, of ANY construction, reaches it's lower limit, thats it, you get nothing more, not even any damping action.

Q: What size of a corner trap would yield the same absortion as a 16" tube trap?

A: If possible, something on the order of 8 feet tall by 8 feet wide, by several feet thick. Even at those dimensions, it still may not equal the full absorbing and damping action of a 16" diameter cylinder-based pressure-type bass trap.

Please note that several companies compare their absorbing devices data to the ASC devices, yet they ALL fail to point out (or perhaps they didn't notice?), that the ASC data is on a PER FOOT BASIS. That means that for a 3 foot tall bass trap, you multiply the absorbing performance by a factor of 3, for a 4 foot tall device, by a factor of 4, etc.

Yet some compare their devices, and claim that they outperform the ASC devices, when in reality, they don't even come close.

Wall panels are not bass traps, and even very fancy "special" wall panels are hard pressed to come close to the actual performance of a pressure based device. You certainly need more than one, or two, or four, to start to come close to equalling what a single 16" diameter bass trap can really do.

It would be nice, actually it would be 'magic', if a single 2 foot by 4 foot panel of ANY thickness could somehow equal even a 12" diameter pressure-trap in terms of damping abnd absorbing bass, but it just ain't so.
Jon Risch
RE: Reply to your specific questions, posted on October 20, 2009 at 00:50:42
crossram2x4@aol.com
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 Hi Jon,

A saw a link (see below) provided on a post by mkuller on a different Tweaker’s Asylum thread where J. Peter Moncrieff states:

“The second harmonics of the room's fundamental bass resonances might need further quelling, even after the fundamental has been controlled to your satisfaction (whatever degree that happens to be). There are several reasons for this. The harmonics are in the upper bass region, which is far more audible to human hearing than lower bass, thus making even a slight remaining resonant boom more objectionable. Also, most music and most loudspeakers put out far more energy in the upper bass than the lower bass, thus triggering even a slight remaining upper bass room resonance mode more frequently and more severely.”

My (very recent and limited) experience in building flat panel traps using 4” thick 24” wide OC 705 leads me to believe that these acoustical treatments have a very positive effect in this way. I did extensive measurements before and after installing these panels, and, while there was no measureable impact to the frequency response in the sub-80hz region, I do hear drastic improvements in mid-bass and midrange linearity, detail, imaging, and overall musicality (perhaps the panels are indeed having a positive impact by shortening the decay time of the bass frequencies). Simply said, the sound is much less thick and ponderous.

Moncrieff goes on to assert that it is the rear (behind the listener) wall-to-wall and wall-to-ceiling intersections that should be treated first by bass traps in order to achieve effective low-bass attenuation. Out of curiosity, tonight I moved my flat panels from the front to the rear corners. Very disappointing. The gains that were achieved with the panels in the front corners were lost. This further leads me to believe that my panels are not significantly affecting the low-bass, but are doing a good bit in the mid-bass and midrange frequencies (in the front corners). I plan to continue to use these in the front corners as they do have a good effect and I have too much time and money invested in them to scrap them. Perhaps I will try to seal them as you recommend to see if I can improve their impact on lower bass frequencies, at least the third harmonic (in my room) of 70 hz.

So, I am now ready to accept that a different solution (tube traps) is indeed needed in the rear corners and horizontally at the rear wall-ceiling intersection to (hopefully) impact the first low-bass fundamental in my room (14.5’ X 23.5' X 10’, so the fundamental is 550/23.5 = 23.4 hz) and, more likely, the second and third harmonics (47 hz and 70 hz). I am thinking of building seven 48” tall 16” diameter traps (stacking two in each rear corner and placing three horizontally between them at the ceiling). I have seen your instructions on building DIY tube traps (not the quick and dirties) and was wondering about the difference in effectiveness when using OC semi-rigid fiberglass panels like ASC uses vs. the batting type you recommend. A while back, a helpful AA member sent me full instructions on how he built tube traps using the semi-rigid fiberglass, but Bill Gates deleted it for me. I do know that OC offers such a product. Do you know what the OC model number is for this type of fiberglass (can be bent uniformly around the chicken wire structure)? How does its performance compare to the batting type? What type of improvement can I expect with the seven 16” tube traps configured as specified above?

For those like me that already have panel-type treatments, perhaps my idea to use them in the corners behind the speakers and real tube-traps in the rear room corners/ceiling is a good solution. I think rather than argue the merits/superiority of each approach, it might be more beneficial for the users just to accept what each does well and work from there.

RE: Reply to your specific questions, posted on October 17, 2009 at 03:59:36
LewinskiH01
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Posts: 40
Joined: December 7, 2008
 Jon,

Thank you so much for your extended replies.

You are correct: I was getting confused. I went through Alton's Master Handbook and started thinking along the lines of a Helmholtz or maybe a panel like resonator straddled in the corner. Then I realized I couldn't straddled them because of the window and started drifting the idea while trying to keep a corner solution...and got confused.

I'm going to try and sell the notion of 12" tube traps to my best half (and see if I can stretch it to 16") for those corners. If that doesn't fly I'll have to resort to absorbing panels, knowing full well performance won't be the same.

BTW, how many 3-feet high by 12" diam. tube traps do you believe will be neccessary to have a meaningfull impact on a 33'x15'x8' room? Beyond broadband absortion, I'm trying to tame an 8 dB peak at 50 Hz (measured with the Radio Shack SPL).

I really appreciate your input!

RE: Reply to your specific questions, posted on October 17, 2009 at 12:04:27
Jon Risch
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 At least four, and better if it were 6 or 8.
Jon Risch
1st, Wall Panels are not Bass Traps, posted on October 16, 2009 at 17:09:08
Jon Risch
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 I have been getting a lot of e-mail lately with folks completely confused about what a bass trap is.

I copy one of my responses down below:

Please realize that the wall panels and the bass traps are two different animals, they serve different purposes, and operate on different principles.

A WALL PANEL, NO MATTER HOW DENSE, IS NOT A BASS TRAP, EVEN IF PLACED IN A CORNER.

The companies that sell simple wall panels as bass traps are doing their customers a dis-service, and creating deep confusion in the marketplace.

A very FEW companies market an advanced design that utilizes a limp membrane in conjunction with a resistive panel to help boost the bass absorption over that of a regular absorbing wall panel, and IF these special types of panels are placed in the corners, they will provide more than ordinary bass absorption. But even these special panels do not match the sheer absorption of the ASC type bass traps, they just don't.

Now, if you really can't use the ASC style bass traps, which my cylindrical traps are a clone of, just a DIY version, then yes, you can beef up the bass absorption of the panel by increasing the density, up to a certain point, and as long as a lower density layer is still present on the front surface to absorb the HF's and upper mids.

The easiest way to achieve this is to compress the regular building grade fiberglass bonded to kraft paper by 2 to 1, and to really do this, you would need to use some chicken wire or animal fencing to deliberately compress the fiberglass on BOTH sides of the 1X4 frame.

OR you can use the higher density semi-rigid panels such as Owen's Corning 705, etc. as an additional layer on the rear of the frame. The more of these, the more low bass absorption UP TO A POINT.

Merely leaning a wall type panel across a corner, no matter how dense (optimally or otherwise), will only absorb so much bass, even the special panels included, although they do absorb a bit more before they 'hit the wall'. In order to absorb any more than this, such a panel would have to be "air-sealed" into the corner, around all edges, so that it created a cavity in the corner, and the only way for the air pressure to get into the corner, was through the panel.

Until you seal a wall panel into the corner like this, it is just a velocity absorber, and not a pressure based absorber, like an ASC style bass trap.

My Super Quick & Dirty bass traps work on the principle of sheer amount of absorbing material of a higher than 'loose' density, but they are still primarily just velocity absorbers. There is some pressure absorption going on, due to the sheer circular diameter of the compressed fiberglass, but not as much as the velocity absorption that is occuring.

I just want you to be aware that no mater how dense, or compressed, you make the wall panels, they are still going to be velocity absorbers, and will not match the effectiveness of the true pressure-absorber bass trap.

END

Jon Risch
Then please define a bass trap…, posted on October 17, 2009 at 01:13:40
David Aiken
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 because at the moment it seems as if you're simply stating that a panel, no matter how effective or how placed, can never be a "bass trap" because it doesn't function as a pressure device.

What is the defining characteristic of a bass trap? Is it:

- mechanism, ie a pressure rather than a velocity device, because a velocity device also reduces sound pressure level—a big problem here is that you have published instructions for a "quick and dirty BASS TRAP that is a velocity rather than a pressure device;

- how it's used, eg a device placed in a particular location—I have some sympathy with this as part of a definition because certain locations are much more optimal placements for a bass trap, whatever that is, than others;

- something which achieves a certain level of effectiveness, but one would need to state the level of effectiveness required as part of the definition.


I'm not trying to be smart but it is possible to build a panel that will be more effective at controlling bass modes when placed in a corner than a tube trap. One simply has to make the panel sufficiently large, thick and dense and the tube trap sufficiently small in diameter and/or height and low in density for the panel to outperform the tube but you're stating here that tube traps are BASS TRAPS and panels aren't, with no qualification of either statement so the implication is that all tube devices are bass traps, all panels aren't, and that bass traps will always control room modes better than a panel when that simply need not be the case.

I'm not trying to ask a trick question. I'm simply saying that your post here doesn't provide reasons to classify tube traps as bass traps and panels as not bass traps and I feel like I'm missing something that's being left implicit and unstated.

I accept that tube traps and panels operate on different principles but so do membrane traps and Helmholtz resonators and at least one other RPG product, all of which are intended to reduce modal behaviour in rooms. What defines one device as a trap and excludes others from being defined as bass traps, especially if the effectiveness of one of the excluded products should exceed that of a product defined as a bass trap?



David Aiken
Part 2, posted on October 19, 2009 at 19:28:11
Jon Risch
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 What is a bass trap?

Is it a wall panel, consisting of a single 2X4 foot sheet of 2" thick fiberglass?

Is it a Helmholtz Resonator, tuned precisely to one frequency?

Or is it something else?

In response to Dave's post, I replied that of the three aspects he cited:

1. Mechanism
2. Placement
3. Effectiveness

I felt that a device that deserved to be called a bass trap would include some of all three.

It would have an effective and efficient mechanism to absorb bass energy, it would be placed where it could absorb and dampen the maximum amount of bass energy, and it would have to have a certain basic level of performance in order to be called a bass trap.

Let's look at the last aspect first. How much bass does a device need to absorb to be called a bass trap.

Let's look at the absorption in Sabin's, standard ASTM conditions, 3rd party data.

Freq in Hz 63 125 250 500

16"dia 3 ft tall
Cylinder Trap 14.9 17.0 15.0 17.8

11"dia 3 ft tall
Cylinder Trap 10.2 10.9 16.7 16.8

2X4 ft 2"
Thick Panel 1.3 1.4 6.9 9.12
(705)

2X4 ft
Specialty 0.7 4.2 12.3 14.2
Panel 1

2X4 ft
Specialty 4.2 9.8 12.8 16.4
Panel 2

Personally, I consider an 11" diameter cylinder trap to be a sort of 'minimum' amount of performance for a bass trap, but that is a bit arbitrary.

However, I think that most people can see that the simple 2 foot by 4 foot by 2" thick fiberglass panel is just NOT a bass trap, by anyone's criteria.

Keep in mind that I recommend the use of a 4 foot tall cylinder trap, this increases the Sabin numbers in the chart by approx. 133% (multiply by 1.33)

In one post about panel traps vs. cylinder traps, it was stated that one 24" (by 48") by 4" thick fiberglass panel (705) was equivalent to a single 20" cylinder trap.

Balderdash.

Freq in Hz 63 125 250 500

20"dia 3 ft tall
Cylinder Trap 14.9 17.0 15.0 17.8

2X4 ft 4"
Thick Panel 3.3 7.2 14.7 13.1
(705)

Also keep in mind that at frequencies below 63 Hz, the cylinder traps are going to be doing something to the bass room modes all the way down to the lowest mode in the room, while the simple panel traps, EVEN IN THE CORNER, will essentially 'go away' for all intents and purposes.

Before we go any further, I know that the panel company folks are going to crawl out of the woodwork and start talking about all kinds of extenuating conditions, and so on.
So, before they cry foul:
Yes, these are ASTM conditions. Not a corner. In some cases, the wall panel data will improve by a factor of 2 at low frequencies when placed in a corner, and at some resonant frequency for the specialty panels, it might even go up to almost three times as much absorption. There, that is out in the open, not to be denied.
But then, let's be fair to the cylinder traps, they will ALSO increase if measured in a corner, perhaps by a factor of 1.5 to 2 times the above data.
This is the point that never get's made in the comparisons of cylinders to wall panels.

This could be because due to ASC patents, they can not offer a cylinder trap for sale, only wall panels. Or it could just be an oversight, a complete coincidence. You decide.

There will also be the question of where the data came from.
The cylinder trap data came from "The Master Handbook of Acoustics", 3rd Ed. by F. Alton Everest. The data is not quite the same as the data on the ASC site, and appears to be a true 3rd party measurement on the entire trap, not just on a "per linear feet" basis, as is the data at the ASC site (in the flyer PDF)
(ASC data: http://tubetrap.com/tubetrap-flyer.pdf
http://www.tubetrap.com/technical.htm )

The data for the 705 panels is widely available, and it has been measured independently from OC, and I did peruse some of these measurements on various acoustics forums, both years ago, and just recently, to make sure they were still out there.

The data I used for the specialty panels comes from the manufacturer's web site, and some of the various brands of specialty panels have been measured by third parties as well. At least the data given at the manufacturer's web site is close to that taken by the third parties.

I still need to explain about aspects #1 and #2, and why these aspects come into play.
And I will explain them, soon, because they explain why even with equal Sabin numbers, the cylinder trap still outperforms a wall panel type. I just thought a few raw numbers first might be fun.

Look for Part 3 soon.

Jon Risch
Bass trap defined, Part 1, posted on October 17, 2009 at 12:45:31
Jon Risch
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 Comment: " Then please define a bass trap ...because at the moment it seems as if you're simply stating that a panel, no matter how effective or how placed, can never be a "bass trap" because it doesn't function as a pressure device.

Reply: I do make a distinction between simple fiberglass wall panels, and wall panels which use additional means of providing bass absorption, so I am not saying that all wall panel type device's are not bass traps.

I did sort of define what I think a bass trap is in my answer up above
( http://www.audioasylum.com/audio/tweaks/messages/16/166034.html ):

In my opinion, a bass trap is a device that is specifically designed to absorb and dampen lower bass frequencies very effectively. It can either depend on a sheer mass of absorbing material, or it can leverage some other absorbing principal, as do the ASC type bass traps.

The typical wall panel is just not thick enough, nor is it large enough to absorb or dampen very much lower bass frequencies.
****************************

However, you asked some very specific questions, and I will endeavor to answer them as best I can.

You mention three things that might define what a bass trap is:
1. Mechanism
2. Placement
3. Effectiveness

In my mind, I think of a bass trap as having all three aspects:
efficient use of pressure style absorption, placement to maximize that pressure absorption mechanism, and enough effectiveness in terms of bass frequency absorption AND bass frequency damping.

In order to explain these criteria, I will need to cover more thoroughly exactly what is a velocity absorber, and what is a pressure absorber.

That is going to take some time to explain, and I will need to take the time to coherently organize and write down these explanations. It will also involve delving into room modes, room boundary stiffness, and a host of other related issues. Trying to condense that down into a single post that is not heroic in length will require even more time and effort.

For the sake of folks who have been confused and even mislead into thinking a simple wall panel placed in the corner is a bass trap, I will try to do so some time in the next few days.

As a short preview to the other side of the coin explanation, yes it is possible to place a flat panel in the corner and get significant bass absorption, even to the point of being able to legitimately being called a "bass trap", but that is not what will happen when the typical "wall panel" consisting of 2 by 4 feet of a few inches of fiberglass is placed in a corner. To think that such a panel is equivalent to an ASC style pressure-principle bass trap is sadly mistaken.


Jon Risch
Thanks for taking the time...., posted on October 18, 2009 at 13:21:38
Oface
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 Well appreciated here....


-chris

RE: Bass trap defined, Part 1, posted on October 17, 2009 at 13:43:09
David Aiken
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Posts: 5111
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 Thanks, Jon. I'll look forward to reading Part 2 when it comes.



David Aiken
RE: Then please define a bass trap…, posted on October 17, 2009 at 08:34:55
Ethan Winer
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Location: New Milford, CT USA
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 > I'm not trying to be smart but it is possible to build a panel that will be more effective at controlling bass modes when placed in a corner than a tube trap. <

Indeed. Bass traps based on rigid fiberglass - whether flat panels, stacked triangles, or filled or hollow tubes - are all velocity absorbers. Rigid fiberglass is a porous material, so sealing the ends or sides etc should have no effect. With velocity absorbers all that matters is they be thick enough, large enough, and you have enough of them placed where bass builds up in the room.

BTW, here's a thread going on now at Audio Circle where a fellow will test some of these theories and post his results:

Comparing "sealed", hollow, insulation tubes to stuffed insulation tubes

--Ethan

RE: DIY corner traps: panel-like or tube-like construction?, posted on October 15, 2009 at 16:02:14
David Aiken
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Location: Brisbane
Joined: September 25, 1999
 "Are corner traps just regular Jon Risch-like panels placed on a corner, or do they have a structure behind?"

They can be either. There is more than one possible design.


"Are their cross-sections fiberglass triangles, ressembling a tube trap but with a triangular section?"

They can be, but I'd only go that way if the hidden sides have a gap between the side and the wall. Sound has to reach the fibreglass from the outside for maximum effect and if the fibreglass is in contact with the wall you lose that feature, reducing effectiveness. If you consider the placement of a tube trap in the corner, there are no points of contact between the tube and the wall, there is an air space all around the tube even if that space may be very narrow at a couple of points.

On the other hand, if you have the whole triangle cross section as solid fibreglass, you do have something that can work effectively in contact with the walls in the corner but I think I'd prefer to go with a panel at 45 degrees across the corner with the air space behind.


"Do they need to be air tight?"

A tube trap isn't air tight. There is a controlled bleed of air through the fibreglass, the fibreglass itself is never going to be air tight. The ASC design tube trap prevents air flow into the interior except through the fibreglass and I think there can be some benefit from that but I suspect maximum benefit comes from matching fibreglass surface area and thickness, fibreglass density, and interior volume.

A panel placed at 45 degrees across the corner also works very effectively, even without a seal to the space behind. My RealTraps Mondo Traps are placed mid height between floor and ceiling and open above and below to the air space behind them. Would I get more effective absorption if they went full height? Yes, but money and room dimensions got in the way of that. They still produce significant benefits placed the way they are.

"What size of a corner trap would yield the same absortion as a 16" tube trap?"

Depends on what density fibreglass you use for each and probably on a couple of other factors.

I'd choose my design based on my construction skills and what I thought would fit into the room best, including factors like cost and also WAF if that is relevant in your case. Then I'd go for the biggest surface area you can get. Whichever design you go for will be highly beneficial if you make them well. Pick a proven design and follow the instructions without modification unless you know what you're doing when you make the modification and if you're asking the questions you've asked then you won't know what you're doing when you make modifications. That's not a put down but a simple observation that if you understand enough to design a trap which varies from other designs, you have to know enough about acoustics and the mechanics of acoustic treatment to be answering rather than asking questions in a forum like this. If you change a design you change the results and if you don't know what you're doing when you change a design, you don't know what the result will be. It may be an improvement and or it may make the trap less effective and you're going to find out the hard way. Go for that if you like experimenting and want to play around and learn things. Don't go that way if you simply want to make some effective DIY treatments for your room.

Pick the proven design you think you can do the best job with, make it, then use as recommended. That's the simplest way to get good results. Then sit back and enjoy.


David Aiken
RE: DIY corner traps: panel-like or tube-like construction?, posted on October 15, 2009 at 19:14:56
LewinskiH01
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Posts: 40
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 Thanks for the thoughtful reply.

I'm now set on absorbing panels at 45 deg on the corners, and looking at the Jon Risch design and the one on the YouTube video linked below which is simply 4" rock wool covered with fabric. Am I right to believe the JR design, with the polyester batting content, is aimed more at absorbing hi frequencies too? Hence, for a bass trap in the corners the batting wouldn't be necessary, so going with the 4" rock wool design would be good enough?

Would you expect much difference in performance in using 4" rock wool vs. 1" rock wool + 4" fiberglass (a la Risch)?

Thanks again!

RE: DIY corner traps: panel-like or tube-like construction?, posted on October 15, 2009 at 23:53:02
David Aiken
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 The polyester batting in the JR design is intended to prevent release of fibreglass fibres into the room space. It will have an effect on HF absorption but that won't be critical with corner placement since it will only affect later reflections, not first reflections. Personally I would not omit the polyester because of health issues with fibreglass fibres getting in the lungs, especially if you have young children in the house.

Can't comment on the differences between 4" rock wool vs 1" rock wool plus 4" fibreglass. I haven't tried either approach and haven't seen comparative measurement data.



David Aiken
RE: DIY corner traps: panel-like or tube-like construction?, posted on October 15, 2009 at 12:29:41
felrob
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 I just finished installing built in "super chunk" style bass traps in the corners behind my speakers, in the living room. Like you, I had WAF considerations, although it turned out that she was more accepting than I thought she would be.

The sound improvement was wonderful, and they don't really feel like they are taking up a lot of room, so it's a win-win.

Here's the thread I had in the Rives forum that allowed me to gather up courage to tweak the living room.

http://www.audioasylum.com/cgi/vt.mpl?f=rives&m=6020

Have fun!

RE: DIY corner traps: panel-like or tube-like construction?, posted on October 15, 2009 at 18:19:35
LewinskiH01
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 Thank you!

I had seen your thread at the Rives forum a few days after you started it, but hadn't seen the outcome. Thanks for the link. We are still waiting for pictures, BTW! :-)

RE: DIY corner traps: panel-like or tube-like construction?, posted on October 16, 2009 at 10:46:03
felrob
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 You're welcome! Pictures...I *still* haven't finished the trim, lazy bastard that I am. Hopefully this weekend, and then I promise to post a picture of the finished product.

RE: DIY corner traps: panel-like or tube-like construction?, posted on October 31, 2009 at 17:10:41
felrob
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I finally got around to taking pictures as requested, but they didn't turn out so well. Here is one that at least gives an idea of how the corner traps look, although the picture quality is not good. The bass trap quality, however is excellent!

RE: DIY corner traps: panel-like or tube-like construction?, posted on November 1, 2009 at 05:03:42
LewinskiH01
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 That looks good!

I have finally decided on making tube traps for my front corners. It will take me a few weeks, as time is scarce, but I'm at it. Got some materials already.

Later on I suspect I'll experiment with panels for first reflection points.
High Density fiberglass will absorb bass..., posted on October 15, 2009 at 08:53:38
Paul_A
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 ...and I didn't want to put a big trap in the corner, so I made a built-in. This configuration may not be ideal, but it does absorb bass.






In the opposite corner, I had no room for a free standing bass trap, so I made a recess in the wall at the end of my CD shelves. I filled both cavities with 7pcf fiberglass at the front of the trap and 5 pcf in the back. In front of the fiberglass is polyester batting, and the finish surface is fabric from Guilford of Maine.
RE: High Density fiberglass will absorb bass..., posted on October 15, 2009 at 18:21:48
LewinskiH01
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Posts: 40
Joined: December 7, 2008
 Nice looking traps. Too bad I can't do something like this. The "front wall" is a large sliding door/window, so I can't really implement this.

Good idea, though!

RE: DIY corner traps: panel-like or tube-like construction?, posted on October 14, 2009 at 22:35:38
crossram2x4@aol.com
Audiophile

Posts: 299
Joined: April 17, 2008
 "Are corner traps just regular Jon Risch-like panels placed on a corner, or do they have a structure behind?"

See the video on how to build DIY flat traps on the link below. Use FRK OC 705 (faced panels for the front 2" layer and non-faced for the rear 2" layer and then cover them with thin plastic before covering with fabric. Floor-to-ceiling is best.

"Are their cross-sections fiberglass triangles, resembling a tube trap but with a triangular section?"

No.

"Do they need to be air tight?"

No.

"What size of a corner trap would yield the same absortion as a 16" tube trap?"

Ethan Winer has posted saying that 24" wide 4" thick OC705 flat traps are equivalent in absorption to a 20" tube trap.

The is a lot of helpful info on the Rives Audio asylum. Read it.

Good luck.

RE: DIY corner traps: panel-like or tube-like construction?, posted on October 15, 2009 at 18:17:03
LewinskiH01
Audiophile

Posts: 40
Joined: December 7, 2008
 Thank you.

Yup, I had seen the tutorial through the other DIY traps thread. Easy-peasey!

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